The removal of ammonia from wastewaters after secondary biological treatment can successfully be achieved by ion exchange. However, the presence of residual organic compounds can impart significant influence on the uptake and their presence may need to be considered during the design of a treatment system. The aim of this work was to determine the effect of the presence of certain organic compounds upon the uptake of ammonium ion and column breakthrough. Two organic contaminants were considered, including citric acid and protein (as whey protein isolate). Three cationic exchangers were used and included the natural zeolite clinoptilolite, the gel resin Dowex 50w-x8, and a macronet resin, Purolite MN-500. The influence of regeneration upon column breakthrough behaviour was also determined. The results showed that the presence of organic compounds had variable effects on ammonium ion uptake. In the case of clinoptilolite the presence of protein appeared to have very little effect upon breakthrough capacity. In the case of the clinoptilolite and the MN500 a substantial reduction of breakthrough capacity was observed in the presence of citric acid. In the case of clinoptilolite a very significant increase in column breakthrough performance was observed after cycles of exhaustion and regeneration. This was not observed in the case of the synthetic resins, which showed a more consistent performance from run to run. Overall the Dowex50w-x8 gave the highest breakthrough capacity for ammonium ion removal of 700 bed volumes. Regenerated clinoptilolite showed a maximum breakthrough capacity of 450 bed volumes, and MN-500 a consistent breakthrough capacity of 300 bed volumes.
The continuous removal of ammonium ions and other ionic pollutants from waste waters can be successfully achieved, usually after secondary biological treatment operations, by using ion exchange. In actual industrial operations, the presence of small concentrations of other non‐ionic or weakly ionic pollutants may exert significant influence upon the ion‐exchange uptake of the ionic species. Such effects are of significant importance in the design and specification of ion‐exchange treatment systems. The underlying aim of the work described in this paper was to quantify the behaviour of the naturally occurring zeolite, clinoptilolite, during the removal of ammonium ion in fixed‐bed ion‐exchange columns in the presence of contaminants. There were two specific areas of investigation. Firstly, the effects of interfering species, including the organic compounds citric acid, phenol, hexane, glucose, natural sunflower oil and whey protein, were studied. The effect of the presence of these contaminants upon the column breakthrough behaviour was determined. Secondly, the effect of regeneration upon the ion‐exchange performance was measured over a number of uptake/regeneration cycles. The results show that the presence of citric acid had only a small effect upon column breakthrough capacity. The column performance in the presence of whey protein is slightly enhanced. The column uptake performance is significantly enhanced after regeneration over the first four to five cycles of regeneration until a stable exchange performance is attained. The enhancement was also observed in the presence of the contaminants. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.
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